The Chilkat online reference documentation for the CkByteData class, concerning the methods for copying Java byte arrays into and out of a CkByteData object, are incorrect.

This is the correct way to do it:

CkByteData byteData = new CkByteData();

// Create a Java byte array with some bytes..
byte[] myData = "Any String you want".getBytes();

// Copy the bytes from the Java byte array into the CkByteData.
byteData.appendByteArray(myData);

// Copy the bytes from the CkByteData to a new Java byte array.
byte[] myData2 = byteData.toByteArray();